SM UC-66

SM UC-66 was a German Type UC II minelaying submarine, or U-boat, of the Imperial German Navy (Kaiserliche Marine) during World War I. She was commissioned on June 27, 1917, and served in the Flanders Flotilla. UC-66 was credited with sinking 43 ships with a combined tonnage of 102,781 gross register tons (GRT), damaging 10 ships with a combined tonnage of 28,260 GRT, and taking one ship as a prize.

Her career primarily involved laying mines in the English Channel and off the coast of France. These mines proved highly effective, contributing significantly to Allied shipping losses.

On June 2, 1918, UC-66 was sunk in the English Channel, near Boulogne, France, by the British armed trawler HMS Leith. There were no survivors.